The invention relates to an apparatus for open end friction spinning with two adjacently arranged friction rollers driven in the same rotational direction forming a yarn forming wedge shaped gap. A fiber opening device is provided for opening fibers to be spun and a fiber feed channel leads from the opening device to the yarn forming gap. A yarn withdrawal device is also provided for drawing off the produced yarn in the direction of the longitudinal extension of the wedge shaped yarn forming gap.
Apparatus of the above-mentioned type is described in German Published Unexamined Application (DE-OS) 28 10 184 whereby high delivery speeds for the produced yarn are desired making it necessary to supply a great amount of fiber material to the wedge-shaped gap. However, there are limits to the increasing of the supply of fiber material by increasing the supply speed and dependent thereupon the rotational speed of the opening device opening roller since a careful handling of the fibers is still necessary if the desired good opening of fiber material to single fibers is to be maintained.
It has been contemplated to simultaneously feed and open several fiber bands for an increase in the amount of fibers to be fed in. With such arrangements, the supply of fibers from the opening device to the yarn forming gap does not occur by means of channels but to a great extent in a free flight. With such arrangements, only a very rough yarn can be spun because the fibers uncontrollably reach the yarn forming gap and are deposited there in an uncontrollable manner.
It is an object of the present invention to so design an arrangement of the above-mentioned type that a greater amount of fiber material is supplied without damage to the fiber material whereby the deposition of the fibers in the yarn forming gap itself occurs in a controlled manner.
This object is achieved in accordance with the present invention in that the opening device is so arranged to allow a simultaneous opening of several fiber bands and in that the fiber feed channel is divided in its cross-section in several sections, the mouths of the feed channel sections being disposed to open to the yarn forming gap at least partially one behind the other along the longitudinal extension of the yarn forming gap.
With the arrangement of the invention, the fibers are guided in a controllable manner from the opening roller to the yarn forming gap and are deposited via several feed channel section areas which are distributed along the length of the yarn forming gap. It is thereby obtained that without an increase of the operational speed of the opening device, not only a greater amount of fiber material is supplied, but also a so-called return doubling occurs, displaying a greater uniformity of the yarn to be produced since the supplied fibers are deposited at several areas. Thereby a further improvement in the uniformity of the yarn to be produced is obtained. If one would utilize a fiber feed channel with a completely free and undivided cross-section rather than the present invention, a fiber feed air stream and associated fiber stream would result with a majority of the supplied fibers being transferred to a preferred position at the yarn forming gap or the associated inwardly turning roller surfaces. An excessive amount of fibers would then exist in this area making the spinning of a uniform and qualitative good yarn impossible.
In a preferred embodiment of the invention, the opening device includes an opening roller the actual length of which is chosen to allow at least two fiber bands to be adjacently supplied thereto, wherein a respective portion or section of the fiber feed channel is disposed to accommodate fibers from each fiber band beginning at the opening roller. These fiber feed channel sections thereby form a separate guide or channel for each fiber band, which channel sections are so-designed especially in the area of the feed channel mouth that the fibers to be transported there are optimally deposited. By using only one opening roller, the additional expenditures necessary for accommodating the increased fiber amount to be supplied is minimized.
In a further embodiment of the invention, the opening device includes an inlet roller and joint feed table designed for supplying several adjacently arranged fiber bands to the opening roller. This kind of inlet and opening device is not much different in principle from the known inlet and opening devices with open-end rotor spinning machines with the exception of a greater axial extension, whereby the manufacturing costs are not essentially greater than for such arrangements.
Another embodiment of the invention is provided, wherein the opening device includes an inlet roller for several adjacently arranged fiber bands, including a single separate feed table for each fiber band respectively. By using single feed tables, an optimal control of the supplying and the opening of each fiber band is obtained and fiber bands of different fiber materials can be supplied and opened. The installation of single-feed tables accommodates individual adjustment of the pressure applied against the joint inlet roller. In the event that different inlet speeds are desired for individual fiber bands it is also contemplated to divide the inlet roller into multiple inlet rollers and/or to provide an inlet roller with stepped different diameters for different fiber bands.
In yet another embodiment of the invention it is provided that the fiber feed channel exhibits a rectangular cross-section at least in its end area facing the opening roller, extending with its greater length parallel to the axle or axis of the opening roller. The fiber feed channel is thus thereby configured to conform to the widened opening roller.
In another embodiment of the invention it is provided that the fiber feed channel is divided into sections by means of at least one partitioning wall starting in a radial plane to the opening roller. The relatively large fiber feed channel is thereby divided into several small channels by a simple means so that the air stream and thereby the fiber transport is well controlled. The partitioning walls in a favorable manner do not begin directly at the opening roller, but at a certain distance so that the entire work area of the opening roller is utilized. It is further advantageous if the partitioning wall or the partitioning walls extend only a portion of the cross-section of the channel. Thereby the airstream and further the fiber stream is favorably influenced whereby fibers cannot get stuck along the outer edges of the partitioning walls.
In yet another embodiment of the invention it is provided that the partitioning wall or the partitioning walls taper knife blade like to a decreasing size in the fiber transport direction in the area of the feed channel section mouths. The mouth areas of the individual sections thus merge together uniformly to a great extent.
A yet further embodiment of the invention is provided wherein the mouths of the feed channel sections are laterally arranged adjacent each other to the yarn forming cap whereby one section mouth is positioned approximately above the yarn forming gap while the other section mouth or mouths are arranged opposite the cover surface of the roller rotating into the yarn forming gap. The arrival of fibers through the section mouths that are positioned at a distance to the yarn forming gap are exposed to a minor lateral motion before they reach the yarn forming gap. A certain effect is thus obtained with the tying up of these fibers.
In yet a further embodiment of the invention it is provided that the partitioning walls are adjustably arranged in position within the fiber feed channel. It is also contemplated to adjust the partitioning wall to a favorable position for a respective fiber material.
In a further embodiment of the invention it is provided that the fiber feed channel is arranged at a sharp angle to the yarn forming gap. Thereby the feed channel section mouths extend with a relatively large portion in the direction of the yarn forming gap so that a good fiber distribution is obtained over the entire yarn formation area.
In another embodiment of the invention the opening roller is divided into respective zones for each fiber band. It is thereby contemplated to provide the opening roller with a ring band between said zones. It is advantageous if the opening roller includes zones which are arranged with different mountings (settings) when supplying fiber bands of different materials, according to certain preferred embodiments of the invention. This for example, would permit supplying fiber bands of different materials with fibers that are responsible for the tenacity of the yarn to be produced being supplied first so that the same reach the center of the yarn to be produced while fibers that are merely designed for the appearance of the yarn are supplied later, thereby forming essentially the cover of the yarn.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.